Cannot find spacing button
That person probably used the space tool from the LoopTools Addon.



To activate the LoopTools Addon, go to the User Preferences Window and find the Addon in the Addons tab (CtrlAltU > Addons > Mesh > LoopTools), then Check the little checkbox on the right.

After selecting a bunch of verts, use the Space Tool from the Tools Shelf > Tools tab > Looptools, or via the Specials Menu (W) > LoopTools > Space.